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“Effect of edge groups on the electronic transport properties of tetrapodal diazatriptycene molecule”. Berdiyorov GR, Peeters FM, Hamoudi H, Physica. E: Low-dimensional systems and nanostructures 141, 115212 (2022). http://doi.org/10.1016/J.PHYSE.2022.115212
Abstract: We conduct ballistic transport calculations to study the electronic transport properties of diazatriptycene molecule which can be self-assembled on metallic surfaces with uniform coverage and upright orientation of the functional head group. Due to its structural asymmetry, the molecule shows a clear current rectification, where the level of the rectification depends on the nature of the head group. For example, current rectification can be increased by more than a factor of 2 by anchoring the molecules to the electrode by CN functional group or introducing insulating CH2 group between the thiol end group and the adjacent phenyl ring. Our findings show the possibility of creating self-assembled monolayer of DAT molecules with controlled electronic transport properties through functionalization of the head group.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 3.3
Times cited: 2
DOI: 10.1016/J.PHYSE.2022.115212
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“A comprehensive modelling approach for the neutral atmospheric boundary layer : consistent inflow conditions, wall function and turbulence model”. Parente A, Gorlé, C, van Beeck J, Benocci C, Boundary-layer meteorology 140, 411 (2011). http://doi.org/10.1007/s10546-011-9621-5
Abstract: We report on a novel approach for the Reynolds-averaged Navier-Stokes (RANS) modelling of the neutral atmospheric boundary layer (ABL), using the standard k− turbulence model. A new inlet condition for turbulent kinetic energy is analytically derived from the solution of the k− model transport equations, resulting in a consistent set of fully developed inlet conditions for the neutral ABL. A modification of the standard k− model is also employed to ensure consistency between the inlet conditions and the turbulence model. In particular, the turbulence model constant C μ is generalized as a location-dependent parameter, and a source term is introduced in the transport equation for the turbulent dissipation rate. The application of the proposed methodology to cases involving obstacles in the flow is made possible through the implementation of an algorithm, which automatically switches the turbulence model formulation when going from the region where the ABL is undisturbed to the region directly affected by the building. Finally, the model is completed with a slightly modified version of the Richards and Hoxey rough-wall boundary condition. The methodology is implemented and tested in the commercial code Ansys Fluent 12.1. Results are presented for a neutral boundary layer over flat terrain and for the flow around a single building immersed in an ABL.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.573
Times cited: 54
DOI: 10.1007/s10546-011-9621-5
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“Electron microscopy and mass-spectrometry study of In GaAsP/InP heterostructures (p-i-n diodes) grown by liquid phase epitaxy”. Volkov VV, Luyten W, van Landuyt J, Férauge C, Oksenoid KG, Gijbels R, Vasilev MG, Shelyakin AA, Lazarev VB, Physica status solidi: A: applied research 140, 73 (1993). http://doi.org/10.1002/pssa.2211400105
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 7
DOI: 10.1002/pssa.2211400105
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“Electron microscopy and mass-spectrometry study of In0.72Ga0.28As0.62P0.38 lasers grown by liquid phase epitaxy”. Luyten W, Volkov VV, van Landuyt J, Amelinckx S, Férauge C, Gijbels R, Vasilev MG, Shelyakin AA, Lazarev VB, Physica status solidi: A: applied research 140, 453 (1993). http://doi.org/10.1002/pssa.2211400216
Abstract: Broad area as well as buried heterostructure lasers based on In0.72Ga0.28As0.62P0.38/InP and emitting at 1.3 mum are grown by liquid phase epitaxy and are studied in detail by means of transmission electron microscopy, X-ray diffraction, secondary ion mass-spectrometry, and electroluminescence. The InGaAsP epilayer is found to be well lattice-matched and of good structural quality. A tentative explanation is presented for the spinodal decomposition observed in the InGaAsP alloy. We also report on the high performance characteristics of the infrared lasers.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 3
DOI: 10.1002/pssa.2211400216
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“Electronic properties of graphene nano-flakes : energy gap, permanent dipole, termination effect, and Raman spectroscopy”. Singh SK, Neek-Amal M, Peeters FM, The journal of chemical physics 140, 074304 (2014). http://doi.org/10.1063/1.4865414
Abstract: The electronic properties of graphene nano-flakes (GNFs) with different edge passivation are investigated by using density functional theory. Passivation with F and H atoms is considered: C-Nc X-Nx (X = F or H). We studied GNFs with 10 < N-c < 56 and limit ourselves to the lowest energy configurations. We found that: (i) the energy difference Delta between the highest occupied molecular orbital and the lowest unoccupied molecular orbital decreases with N-c, (ii) topological defects (pentagon and heptagon) break the symmetry of the GNFs and enhance the electric polarization, (iii) the mutual interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, (iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and (v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination, and bilayer on the electronic properties of small GNFs. This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.965
Times cited: 30
DOI: 10.1063/1.4865414
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“Applying digital image processing to SEM-EDX and BSE images to determine and quantify porosity and salts with depth in porous media”. Cardell C, Yebra A, Van Grieken RE, Microchimica acta 140, 9 (2002). http://doi.org/10.1007/S006040200063
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1007/S006040200063
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“Observation of Sb203 nanocrystals in SiO2 after Sb ion implantation”. Ignatova VA, Lebedev OI, Wätjen U, van Vaeck L, van Landuyt J, Gijbels R, Adams F, Microchimica acta 139, 77 (2002). http://doi.org/10.1007/s006040200043
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.58
Times cited: 3
DOI: 10.1007/s006040200043
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“Structural and microstructural aspects of Six(Ta, Nb)Te2”. Frangis N, Van Tendeloo G, Manolikas C, Amelinckx S, Journal of solid state chemistry 139, 105 (1998). http://doi.org/10.1006/jssc.1998.7815
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 2
DOI: 10.1006/jssc.1998.7815
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“The structure and manipulation of vortex states in a superconducting square with 2 ×, 2 blind holes”. Berdiyorov GR, Milošević, MV, Peeters FM, Journal of low temperature physics 139, 229 (2005). http://doi.org/10.1007/s10909-005-3926-z
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.3
Times cited: 4
DOI: 10.1007/s10909-005-3926-z
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“Vortex-antivortex lattices in superconducting films with magnetic pinning arrays”. Milošević, MV, Peeters FM, Journal of low temperature physics 139, 257 (2005). http://doi.org/10.1007/s10909-005-3929-9
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.3
Times cited: 12
DOI: 10.1007/s10909-005-3929-9
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“High-Yield Seeded Growth of Monodisperse Pentatwinned Gold Nanoparticles through Thermally Induced Seed Twinning”. Sánchez-Iglesias A, Winckelmans N, Altantzis T, Bals S, Grzelczak M, Liz-Marzán LM, Journal of the American Chemical Society 139, 107 (2016). http://doi.org/10.1021/jacs.6b12143
Abstract: We show here that thermal treatment of small seeds results in extensive twinning and a subsequent drastic yield improvement (>85%) in the formation of pentatwinned nanoparticles, with pre-selected morphology (nanorods, bipyramids and decahedra) and aspect ratio. The “quality” of the seeds thus defines the yield of the obtained nanoparticles, which in the case of nanorods avoids the need for additives such as Ag+ ions. This modified seeded growth method also improves reproducibility, as the seeds can be stored for extended periods of time without compromising the quality of the final nanoparticles. Additionally, minor modification of the seeds with Pd allows their localization within the final particles, which opens new avenues toward mechanistic studies. All together, these results represent a paradigm shift in anisotropic gold nanoparticle synthesis.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 267
DOI: 10.1021/jacs.6b12143
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“Highly Emissive Divalent-Ion-Doped Colloidal CsPb1–xMxBr3Perovskite Nanocrystals through Cation Exchange”. van der Stam W, Geuchies JJ, Altantzis T, van den Bos KHW, Meeldijk JD, Van Aert S, Bals S, Vanmaekelbergh D, de Mello Donega C, Journal of the American Chemical Society 139, 4087 (2017). http://doi.org/10.1021/jacs.6b13079
Abstract: Colloidal CsPbX3 (X = Br, Cl, and I) perovskite nanocrystals (NCs) have emerged as promising phosphors and solar cell materials due to their remarkable optoelectronic properties. These properties can be tailored by not only controlling the size and shape of the NCs but also postsynthetic composition tuning through topotactic
anion exchange. In contrast, property control by cation exchange is still underdeveloped for colloidal CsPbX3 NCs. Here, we present a method that allows partial cation exchange in colloidal CsPbBr3 NCs, whereby Pb2+ is exchanged for several isovalent cations, resulting in doped CsPb1−xMxBr3 NCs (M= Sn2+, Cd2+, and Zn2+; 0 < x ≤ 0.1), with preservation of the original NC shape. The size of the parent NCs is also preserved in the product NCs, apart from a small (few
%) contraction of the unit cells upon incorporation of the guest cations. The partial Pb2+ for M2+ exchange leads to a blue-shift of the optical spectra, while maintaining the high photoluminescence quantum yields (>50%), sharp absorption features, and narrow emission of the parent CsPbBr3 NCs. The blue-shift in the optical spectra is attributed to the lattice contraction that accompanies the Pb2+ for M2+ cation exchange and is observed to scale linearly with the lattice contraction. This work opens up new possibilities to engineer the properties of halide perovskite NCs, which to date are demonstrated to be the only known
system where cation and anion exchange reactions can be sequentially combined while preserving the original NC shape, resulting in compositionally diverse perovskite NCs.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 535
DOI: 10.1021/jacs.6b13079
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“1D-2D-3D Transformation Synthesis of Hierarchical Metal-Organic Framework Adsorbent for Multicomponent Alkane Separation”. Wee LH, Meledina M, Turner S, Van Tendeloo G, Zhang K, Marleny Rodriguez-Albelo L, Masala A, Bordiga S, Jiang J, Navarro JAR, Kirschhock CEA, Martens JA, Journal of the American Chemical Society 139, 819 (2017). http://doi.org/10.1021/JACS.6B10768
Abstract: A new hierarchical MOF consisting of Cu(II) centers connected by benzene-tricarboxylates (BTC) is prepared by thermoinduced solid transformation of a dense CuBTC precursor phase. The mechanism of the material formation has been thoroughly elucidated and revealed a transformation of a ribbon-like 1D building unit into 2D layers and finally a 3D network. The new phase contains excess copper, charge compensated by systematic hydroxyl groups, which leads to an open microporous framework with tunable permanent mesoporosity. The new phase is particularly attractive for molecular separation. Energy consumption of adsorptive separation processes can be lowered by using adsorbents that discriminate molecules based on adsorption entropy rather than enthalpy differences. In separation of a 11-component mixture of C-1-C-6 alkanes, the hierarchical phase outperforms the structurally related microporous HKUST-1 as well as silicate-based hierarchical materials. Grand canonical Monte Carlo (GCMC) simulation provides microscopic insight into the structural host-guest interaction, confirming low adsorption enthalpies and significant entropic contributions to the molecular separation. The unique three-dimensional hierarchical structure as well as the systematic presence of Cu(II) unsaturated coordination sites cause this exceptional behavior.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 33
DOI: 10.1021/JACS.6B10768
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“Room Temperature Magnetically Ordered Polar Corundum GaFeO3 Displaying Magnetoelectric Coupling”. Niu H, Pitcher MJ, Corkett AJ, Ling S, Mandal P, Zanella M, Dawson K, Stamenov P, Batuk D, Abakumov AM, Bull CL, Smith RI, Murray CA, Day SJ, Slater B, Cora F, Claridge JB, Rosseinsky MJ, Journal of the American Chemical Society 139, 1520 (2017). http://doi.org/10.1021/jacs.6b11128
Abstract: The polar corundum structure type offers a route to new room temperature multiferroic materials, as the partial LiNbO3-type cation ordering that breaks inversion symmetry may be combined with long-range magnetic ordering of high spin d(5) cations above room temperature in the AFeO(3) system. We report the synthesis of a polar corundum GaFeO3 by a high-pressure, high-temperature route and demonstrate that its polarity arises from partial LiNbO3 -type cation ordering by complementary use of neutron, X-ray, and electron diffraction methods. In situ neutron diffraction shows that the polar corundum forms directly from AlFeO3-type GaFeO3 under the synthesis conditions. The A(3+)/Fe3+ cations are shown to be more ordered in polar corundum GaFeO3 than in isostructural ScFeO3. This is explained by DFT calculations which indicate that the extent of ordering is dependent on the configurational entropy available to each system at the very different synthesis temperatures required to form their corundum structures. Polar corundum GaFeO3 exhibits weak ferromagnetism at room temperature that arises from its Fe2O3-like magnetic ordering, which persists to a temperature of 408 K. We demonstrate that the polarity and magnetization are coupled in this system with a measured linear magnetoelectric coupling coefficient of 0.057 ps/m. Such coupling is a prerequisite for potential applications of polar corundum materials in multiferroic/magnetoelectric devices.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 12
DOI: 10.1021/jacs.6b11128
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“Martensite crystallography and chemistry in dual phase and fully martensitic steels”. Du C, Hoefnagels JPM, Kolling S, Geers MGD, Sietsma J, Petrov R, Bliznuk V, Koenraad PM, Schryvers D, Amin-Ahmadi B, Materials characterization 139, 411 (2018). http://doi.org/10.1016/j.matchar.2018.03.011
Abstract: Lath martensite is important in industry because it is the key strengthening component in many advanced high strength steels. The study of crystallography and chemistry of lath martensite is extensive in the literature, however, mostly based on fully martensitic steels. In this work, lath martensite in dual phase steels is investigated with a focus on the substructure identification of the martensite islands and microstructural bands using electron backscattered diffraction, and on the influence of the accompanied tempering process during industrial coating process on the distribution of alloying elements using atom probe tomography. Unlike findings for the fully martensitic steels, no martensite islands with all 24 Kurdjumov-Sachs variants have been observed. Almost all martensite islands contain only one main packet with all six variants and minor variants from the remaining three packets of the same prior austenite grain. Similarly, the martensite bands are typically composed of connected domains originating from prior austenite grains, each containing one main packets (mostly with all variants) and few separate variants. The effect of tempering at similar to 450 degrees C (due to the industrial zinc coating process) has also been investigated. The results show a strong carbon partitioning to lath boundaries and Cottrell atmospheres at dislocation core regions due to the thermal process of coating. In contrast, auto-tempering contributes to the carbon redistribution only in a limited manner. The substitutional elements are all homogenously distributed. The phase transformation process has two effects on the material: mechanically, the earlier-formed laths are larger and softer and therefore more ductile (as revealed by nanoindentation); chemically, due to the higher dislocation density inside the later-formed laths, which are generally smaller, carbon Cottrell atmospheres are predominantly observed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 2.714
DOI: 10.1016/j.matchar.2018.03.011
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“Macroscopic Fourier transform infrared scanning in reflection mode (MA-rFTIR), a new tool for chemical imaging of cultural heritage artefacts in the mid-infrared range”. Legrand S, Alfeld M, Vanmeert F, de Nolf W, Janssens K, The analyst 139, 2489 (2014). http://doi.org/10.1039/C3AN02094K
Abstract: In this paper we demonstrate that by means of scanning reflection FTIR spectroscopy, it is possible to record highly specific distribution maps of organic and inorganic compounds from flat, macroscopic objects with cultural heritage value in a non-invasive manner. Our previous work involved the recording of macroscopic distributions of chemical elements or crystal phases from painted works of art based on respectively macroscopic X-ray fluorescence or X-ray powder diffraction analysis. The use of infrared radiation instead of X-rays has the advantage that more specific information about the nature and distribution of the chemical compounds present can be gathered. This higher imaging specificity represents a clear advantage for the characterization of painting and artist materials. It allows the distribution of metallo-organic compounds to be visualized and permits distinguishing between pigmented materials containing the same key metal. The prototype instrument allows the recording of hyperspectral datacubes by scanning the surface of the artefact in a contactless and sequential single-point measuring mode, while recording the spectrum of reflected infrared radiation. After the acquisition, spectral line intensities of individual bands and chemical distribution maps can be extracted from the datacube to identify the compounds present and/or to highlight their spatial distribution. Not only is information gained on the surface of the investigated artefacts, but also images of overpainted paint layers and, if present, the underdrawing may be revealed in this manner. A current major limitation is the long scanning times required to record these maps.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.885
Times cited: 25
DOI: 10.1039/C3AN02094K
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“Airborne bacteria in the atmosphere : presence, purpose, and potential”. Smets W, Moretti S, Denys S, Lebeer S, Atmospheric environment : an international journal 139, 214 (2016). http://doi.org/10.1016/J.ATMOSENV.2016.05.038
Abstract: Numerous recent studies have highlighted that the types of bacteria present in the atmosphere often show predictable patterns across space and time. These patterns can be driven by differences in bacterial sources of the atmosphere and a wide range of environmental factors, including UV intensity, precipitation events, and humidity. The abundance of certain bacterial taxa is of interest, not only for their ability to mediate a range of chemical and physical processes in the atmosphere, such as cloud formation and ice nucleation, but also for their implications -both beneficial and detrimental-for human health. Consequently, the widespread importance of airborne bacteria has stimulated the search for their applicability. Improving air quality, modelling the dispersal of airborne bacteria (e.g. pathogens) and biotechnological purposes are already being explored. Nevertheless, many technological challenges still need to be overcome to fully understand the roles of airborne bacteria in our health and global ecosystems.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.ATMOSENV.2016.05.038
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“Application of thin-window EPMA to environmental problems in Hungary”. Osán J, Kurunczi S, Török S, Worobiec A, Van Grieken R, Microchimica acta 139, 111 (2002). http://doi.org/10.1007/S006040200048
Keywords: A1 Journal article; Laboratory Experimental Medicine and Pediatrics (LEMP); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1007/S006040200048
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“Damage functions and mechanism equations derived from limestone weathering in field exposure”. Delalieux F, Cardell-Fernandez C, Torfs K, Vleugels G, Van Grieken RE, Water, air and soil pollution 139, 75 (2002). http://doi.org/10.1023/A:1015827031669
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1023/A:1015827031669
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“Terahertz optoelectronic properties of synthetic single crystal diamond”. Xiao H, Zhang Z, Xu W, Wang Q, Xiao Y, Ding L, Huang J, Li H, He B, Peeters FM, Diamond and related materials 139, 110266 (2023). http://doi.org/10.1016/J.DIAMOND.2023.110266
Abstract: A systematic investigation is undertaken for studying the optoelectronic properties of single crystal diamond (SCD) grown by microwave plasma chemical vapor deposition (MPCVD). It is indicated that, without intentional doping and surface treatment during the sample growth, the terahertz (THz) optical conduction in SCD is mainly affected by surface H-terminations, -OH-, O- and N-based functional groups. By using THz time-domain spectroscopy (TDS), we measure the transmittance, the complex dielectric constant and optical conductivity σ(ω) of SCD. We find that SCD does not show typical semiconductor characteristics in THz regime, where σ(ω) cannot be described rightly by the conventional Drude formula. Via fitting the real and imaginary parts of σ(ω) to the Drude-Smith formula, the ratio of the average carrier density to the effective electron mass γ = ne/m*, the electronic relaxation time τ and the electronic backscattering or localization factor can be determined optically. The temperature dependence of these parameters is examined. From the temperature dependence of γ, a metallic to semiconductor transition is observed at about T = 10 K. The temperature dependence of τ is mainly induced by electron coupling with acoustic-phonons and there is a significant effect of photon-induced electron backscattering or localization in SCD. This work demonstrates that THz TDS is a powerful technique in studying SCD which contains H-, N- and O-based bonds and has low electron density and high dc resistivity. The results obtained from this study can benefit us to gain an in-depth understanding of SCD and may provide new guidance for the application of SCD as electronic, optical and optoelectronic materials.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.1
DOI: 10.1016/J.DIAMOND.2023.110266
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“High-resolution electron microscopy and electron tomography: resolution versus precision”. Van Aert S, den Dekker AJ, van Dyck D, van den Bos A, Journal of structural biology 138, 21 (2002). http://doi.org/10.1016/S1047-8477(02)00016-3
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.767
Times cited: 33
DOI: 10.1016/S1047-8477(02)00016-3
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“Synthesis and structural study of Pb2Re2O7-x pyrochlores”. Abakumov AM, Shpanchenko RV, Antipov EV, Kopnin EM, Capponi JJ, Marezio M, Lebedev OI, Van Tendeloo G, Amelinckx S, Journal of solid state chemistry 138, 220 (1998). http://doi.org/10.1006/jssc.1998.7778
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.299
Times cited: 5
DOI: 10.1006/jssc.1998.7778
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“Supracrystalline Colloidal Eggs: Epitaxial Growth and Freestanding Three-Dimensional Supracrystals in Nanoscaled Colloidosomes”. Yang Z, Altantzis T, Zanaga D, Bals S, Van Tendeloo G, Pileni M-P, Journal of the American Chemical Society 138, 3493 (2016). http://doi.org/10.1021/jacs.5b13235
Abstract: The concept of template-confined chemical reactions allows the synthesis of complex molecules that would hardly be producible through conventional method. This idea was developed to produce high quality nanocrystals more than 20 years ago. However, template-mediated assembly of colloidal nanocrystals is still at an elementary level, not only because of the limited templates suitable for colloidal assemblies, but also because of the poor control over the assembly of nanocrystals within a confined space. Here, we report the design of a new system called “supracrystalline colloidal eggs” formed by controlled assembly of nanocrystals into complex colloidal supracrystals through superlattice-matched epitaxial overgrowth along the existing colloidosomes. Then, with this concept, we extend the supracrystalline growth to lattice-mismatched binary nanocrystal superlattices, in order to reach anisotropic superlattice growths, yielding freestanding binary nanocrystal supracrystals that could not be produced previously.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 57
DOI: 10.1021/jacs.5b13235
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“Topochemical nitridation with anion vacancy -assisted N3-/O2- exchange”. Mikita R, Aharen T, Yamamoto T, Takeiri F, Ya T, Yoshimune W, Fujita K, Yoshida S, Tanaka K, Batuk D, Abakumov AM, Brown CM, Kobayashi Y, Kageyama H;, Journal of the American Chemical Society 138, 3211 (2016). http://doi.org/10.1021/jacs.6b00088
Abstract: We present how the introduction of anion vacancies in oxyhydrides enables a route to access new oxynitrides, by conducting ammonolysis of perovskite oxyhydride EuTiO3-xHx (x similar to 0.18). At 400 degrees C, similar to our studies on BaTiO3-xHx, hydride lability enables a low temperature direct ammonolysis of EUTi3.82+O-2.82/H-0.18, leading to the N3-/H--exchanged product EuTi4+O2.82No0.12 square 0.06 center dot When the ammonolysis temperature was increased up to 800 degrees C, we observed a further nitridation involving N3-/O2- exchange, yielding a fully oxidized Eu3+Ti4+O2N with the GdFeO3-type distortion (Pnma) as a metastable phase, instead of pyrochlore structure. Interestingly, the same reactions using the oxide EuTiO3 proceeded through a 1:1 exchange of N3- with O-2 only above 600 degrees C and resulted in incomplete nitridation to EuTi02.25N0.75, indicating that anion vacancies created during the initial nitridation process of EuTiO2.82H0.18 play a crucial role in promoting anion (N3-/O2-) exchange at high temperatures. Hence, by using (hydride-induced) anion-deficient precursors, we should be able to expand the accessible anion composition of perovskite oxynitrides.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 28
DOI: 10.1021/jacs.6b00088
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“Atomic Structure of Wurtzite CdSe (Core)/CdS (Giant Shell) Nanobullets Related to Epitaxy and Growth”. Bladt E, van Dijk-Moes RJA, Peters J, Montanarella F, de Mello Donega C, Vanmaekelbergh D, Bals S, Journal of the American Chemical Society 138, 14288 (2016). http://doi.org/10.1021/jacs.6b06443
Abstract: Hetero-nanocrystals consisting of a CdSe core and a giant CdS shell have shown remarkable optical properties which are promising for applications in opto-electrical devices. Since these properties sensitively depend on the size and shape, a morphological characterization is of high interest. Here, we present a High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) study of CdSe (core) / CdS (giant shell) hetero-nanocrystals. Electron tomography reveals that the nanocrystals have a bullet shape, either ending in a tip or a small dip, and that the CdSe core is positioned closer to the tip (or dip) than to the hexagonal base. Based on a high resolution HAADF-STEM study, we were able to determine all the surface facets. We present a heuristic model for the different growth stages of the CdS crystal around the CdSe core.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 28
DOI: 10.1021/jacs.6b06443
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“Galvanic Replacement Coupled to Seeded Growth as a Route for Shape-Controlled Synthesis of Plasmonic Nanorattles”. Polavarapu L, Zanaga D, Altantzis T, Rodal-Cedeira S, Pastoriza-Santos I, Pérez-Juste J, Bals S, Liz-Marzán LM, Journal of the American Chemical Society 138, 11453 (2016). http://doi.org/10.1021/jacs.6b06706
Abstract: Shape-controlled synthesis of metal nanoparticles (NPs) requires mechanistic understanding toward the development of modern nanoscience and nanotechnology. We demonstrate here an unconventional shape transformation of Au@Ag core−shell NPs (nanorods and nanocubes) into octahedral nanorattles via roomtemperature galvanic replacement coupled with seeded growth. The corresponding morphological and chemical transformations were investigated in three dimensions, using state-of-the-art X-ray energy-dispersive spectroscopy (XEDS) tomography. The addition of a reducing agent (ascorbic acid) plays a key role in this unconventional mechanistic path, in which galvanic replacement is found to dominate initially when the shell is made of Ag, while seeded growth suppresses transmetalation when a composition of Au:Ag (∼60:40) is reached in the shell, as revealed by quantitative XEDS tomography. This work not only opens new avenues toward the shape control of hollow NPs beyond the morphology of sacrificial templates, but also expands our understanding of chemical transformations in nanoscale galvanic replacement reactions. The XEDS electron tomography study presented here can be generally applied to investigate a wide range of nanoscale morphological and chemical transformations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 75
DOI: 10.1021/jacs.6b06706
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“ZnTaO2N: Stabilized High-Temperature LiNbO3-type Structure”. Kuno Y, Tassel C, Fujita K, Batuk D, Abakumov AM, Shitara K, Kuwabara A, Moriwake H, Watabe D, Ritter C, Brown CM, Yamamoto T, Takeiri F, Abe R, Kobayashi Y, Tanaka K, Kageyama H, Journal of the American Chemical Society 138, 15950 (2016). http://doi.org/10.1021/JACS.6B08635
Abstract: By using a high-pressure reaction, we prepared a new oxynitride ZnTaO2N that crystallizes in a centrosymmetric (R (3) over barc) high-temperature LiNbO3-type structure (HTLN-type). The stabilization of the HTLN-type structure down to low temperatures (at least 20 K) makes it possible to investigate not only the stability of this phase, but also the phase transition to a noncentrosymmetric (R3c) LiNbO3-type structure (LN-type) which is yet to be clarified. Synchrotron and neutron diffraction studies in combination with transmission electron microscopy show that Zn is located at a disordered 12c site instead of 6a, implying an order disorder mechanism of the phase transition. It is found that the dosed d-shell of Zn2+, as well as the high-valent Ta5+ ion, is responsible for the stabilization of the HTLN-type structure, affording a novel quasitriangular ZnO2N coordination. Interestingly, only 3% Zn substitution for MnTaO2N induces a phase transition from LN- to HTLN-type structure, implying the proximity in energy between the two structural types, which is supported by the first-principles calculations.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.858
Times cited: 13
DOI: 10.1021/JACS.6B08635
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“Assessing the stability of arsenic sulfide pigments and influence of the binding media on their degradation by means of spectroscopic and electrochemical techniques”. Vermeulen M, Janssens K, Sanyova J, Rahemi V, McGlinchey C, De Wael K, Microchemical journal 138, 82 (2018). http://doi.org/10.1016/J.MICROC.2018.01.004
Abstract: In this paper, we used the semiconducting and lightfastness properties of synthetic and mineral arsenic sulfide pigments to study their stability by means of electrochemical and microfadometric techniques. A combination of these techniques shows that in the early stage of the degradation process, amorphous arsenic sulfides are more stable than both crystalline forms, while upon longer exposure time, amorphous pigments will fade more than both mineral pigments, making it less suitable. While the stability study was carried out on unbound pigments, the influence of the organic binder on the relative degradation of the arsenic sulfide pigments was investigated through a multi-analytical approach on pigment/binder mock-up paint samples. For this purpose, the formation of arsenic trioxide was assessed by micro Fourier transform infrared (μ-FTIR) spectroscopy while the influence of the binder on the formation of sulfates was studied by means of synchrotron radiation X-ray near edge structure (μ-XANES). Both techniques elucidate a higher stability of all pigments in gum arabic while the use of egg yolk as binder leads to the most degradation, most likely due to its sulfur-rich composition. In the context of the degradation of arsenic sulfide pigments, other binders such as animal glue, egg white or linseed oil show an intermediate impact.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 4
DOI: 10.1016/J.MICROC.2018.01.004
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“Development of a new portable X-ray powder diffractometer and its demonstration to on-site analysis of two selected old master paintings from the Rijksmuseum”. Hirayama A, Abe Y, van Loon A, De Keyser N, Noble P, Vanmeert F, Janssens K, Tantrakarn K, Taniguchi K, Nakai I, Microchemical journal 138, 266 (2018). http://doi.org/10.1016/J.MICROC.2018.01.003
Abstract: A portable X-ray powder diffractometer (p-XRD) PT-APXRD III has been developed for onsite analysis of paintings and archaeological samples. By using a Cu anode X-ray tube and a silicon drift diode (SDD) detector, diffraction patterns with a high signalnoise (S/N) ratio can be recorded. The X-ray tube can be operated at a maximum voltage of 60 kV, which makes it possible to simultaneously record X-ray fluorescence spectra up to the high-energy region. The total weight of this instrument is 16 kg, which can be carried anywhere and the goniometer unit (5.6 kg) can be placed on a tripod for analysis of mural paintings. We brought the instrument to the Rijksmuseum in the Netherlands to examine its applicability for the analysis of oil paintings. We successfully analyzed two seventeenthcentury oil paintings by Johannes Vermeer and Jan Davidsz de Heem (copy after). Ultramarine blue, leadtin yellow type I, and Naples yellow were identified from the diffraction patterns, demonstrating the high practicality of this instrument. Furthermore, it was found from the SEM-EDX analysis of a paint cross section that the yellow pigment was applied in separate layers rather than being mixed. This diffractometer will be commercially available in the near future and will have many applications in the field of material analysis. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 2
DOI: 10.1016/J.MICROC.2018.01.003
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“In situ macro X-ray fluorescence (MA-XRF) scanning as a non-invasive tool to probe for subsurface modifications in paintings by PP Rubens”. van der Snickt G, Legrand S, Slama I, Van Zuien E, Gruber G, Van der Stighelen K, Klaassen L, Oberthaler E, Janssens K, Microchemical journal 138, 238 (2018). http://doi.org/10.1016/J.MICROC.2018.01.019
Abstract: Within the last decade, the established synchrotron- and laboratory-based micro-XRF scanning technology inspired the development of mobile instruments that allow performing in situ experiments on paintings on a macro scale. Since the development of the first mobile scanner at the start of this decade, this chemical imaging technique has brought new insights with respect to several iconic paintings, especially in cases when standard imaging techniques such as X-Ray Radiography (XRR) or Infrared Refiectography (IRR) yielded ambiguous results. The ability of scanning MA-XRF to visualise the distribution of elements detected at and below the paint surface renders this spectrometric method particularly helpful for studying painting techniques and revealing materials that remain hidden below the paint surface. The latter aspect is especially relevant for the technical study of works by Pieter Paul Rubens (1577-1640) as this highly productive seventeenth century master is particularly renowned for the continuous application of modifications during (and even after) the entire course of the creative process. In this work, the added value of MA-XRF scanning experiments for visualising these subsurface features is exemplified by interpreting the chemical images obtained on three of Rubens' key works. Special attention is given to three types of adjustments that are particularly relevant for the technical study of Rubens' oeuvre: (1) compositional changes ('pentimenti'), exemplified by results obtained on The Portrait of Helene Fourment (ca. 1638), (2) extensions to the support ('Anstlickungen.), illustrated by imaging experiments performed on the Venus Frigida (1614) and (3) Rubens' intriguing halos around flesh tones, as found amongst others in The Incredulity of Saint Thomas (1613). The ensuing insights in the paint stratigraphy and the underlying supporting structure illustrate the potential of MA-XRF scanning for the non-invasive, comparative study of Rubens' oeuvre. The results do not only augment the understanding of the complex genesis of Rubens' works of art and his efficient painting technique, but prove valuable during conservation treatments as well, as addressed in this paper. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.034
Times cited: 5
DOI: 10.1016/J.MICROC.2018.01.019
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